The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Many wells, especially in oil fields in deep-water/subsea environments, are completed as open holes that are uncased at the producing section of the well. Because of the extremely high cost of intervention and high production rates, these wells require a reliable completion technique that prevents sand production and maximizes productivity throughout the entire life of the well. One such technique is open-hole gravel packing.
There are two principal techniques used for gravel packing open holes: (1) the alternate path technique and (2) the water packing technique. The latter uses low-viscosity fluids, such as aqueous completion brines to carry the gravel from the surface and deposit it into the annulus between a sand-control screen and the wellbore. The alternate path technique (discussed at least in part in SPE Paper 86532 , on the other hand, utilizes viscous carrier fluids. Therefore the packing mechanisms of these two techniques are significantly different. The alternate path technique allows bypassing of any bridges that may form in the annulus, caused by, for example, high leakoff into the formation due to filtercake erosion, or exceeding the fracturing pressure, or shale-sloughing/shale-swelling or localized formation collapse on the sand control screens.
Most of the recently discovered deep-water fields contain a high fraction of shales, which are water-sensitive, although many have been gravel packed with water-based fluids. A very large fraction of them have been completed with viscous fluids using the alternate path technique. Viscoelastic surfactant (VES) solutions have been the most widely used carrier fluid in open hole gravel packing with the alternate path technique due to their low formation and gravel pack damage characteristics, their low drawdown requirements, their capability of incorporating filtercake cleanup chemicals into the carrier fluid, and their low friction pressures.
While the above-described methods may be adequate for installing sand screens and gravel packing in many wells formed in reactive shale-containing formations, improvements are needed.